One thing is certain, 5-axis CNC
machining has brought the average machine shop light years
ahead. In the past, these machines were reserved only for
large manufacturing operations and thought to be
unattainable for smaller, custom shops.

By Brendan Baker

The fact that CNC machines have
come down in price over the years, coupled with less complicated
interfacing systems means that today they can be used by nearly
anyone. You don’t have to relearn everything. You don’t have to
take endless courses on how to make a tool change. Today’s
machines are sophisticated and savvy enough to take over most of
the legwork and let you concentrate on what you do best.

These days, engine
builders must get as much as possible out of every piece of
equipment in order to make the investment make financial sense.
And with the increasing complexity of performance and late-model
production engines, some shops are forced to the edge of their
older equipment’s capabilities. Shops looking to update older
equipment have many choices today, but many engine builders have
started looking for more than just an improved version of what
they already have.

New CNC machines – from
head porting machines to full machining centers – can automate
repetitive tasks with unmatched precision and, hopefully, pave
the way to future growth.

Millsite’s latest CNC
machine, the Millport Super Red Rhino, incorporates a unique
swivel head that rotates 45 degrees both left and right.This
allows for the machining of those more aggressive port angles
that weren’t previously possible.
The super Red Rhino was designed with versatility in mind, says
Millsite’s John Trusty. “Our quick-change fixturing allows a
rapid change from a 5-axis porting machine to a block boring and
surfacing machine within minutes. It rapidly reproduces and
modifies prototypes. Or just remove the head fixture and put a
machinist vise in its place and begin general 3-axis machining.”

Millsite offers two
methods of digitizing: the old method, consisting of using a
contact probe and recording data points along a surface; and the
new method, which uses a white-light scanner to capture the
desired surfaces.

Millsite’s digitizing
process uses 3D scanning from the old process of using a contact
probe, and has drastically reduced data collection time while
increasing accuracy and repeatability. The 3D scanning process
digitally reconstructs and seamlessly duplicates your original
hand-ground cylinder ports. This has resulted in the digitizing
process, which used to take many days, now being complete in a
matter of hours. The equivalent of about 4 million points are
taken to achieve extreme accuracy.

The art of hand-grinding
ports and getting the perfect shape, along with the desired air
flow results, gets more attention to perfecting the design
instead of having to do every port, while maintaining symmetry.
This process of redesigning ports to eliminate flaws and
maximize the volume and velocity of air can be duplicated and
automated.

Included in the scanning
process is the recording of a reference datum for locating the
surfaces upon importing into CAD/CAM. The time spent struggling
with data to accurately replicate the original surface has been
drastically reduced to a matter of minutes, says Trusty. You no
longer have to manually record data to create a “rough” surface
to 5 axis digitize from. The 3D scanning process also eliminates
issues such as: only recording center-point data, features being
rounded-off by probe-tip diameter, having to offset the surface
to achieve real size, and eliminates any “bad hits,” “shanking,”
or “no hits.”

You don’t have to worry
about the probe getting stuck in small features and tough areas.
You no longer have to patch two sides together, reducing the
possibility of mismatch. And best of all, your machine is free
to use instead of having to wait for digitizing to finish.

Both processes begin with
the hand-ground master ports. Using the probe, the next step is
to use 3-axis with 4+5 positioning to record single curves at
fixed locations. These curves will be used to make the rough
surface. A 5 axis digitizing toolpath is created on that surface
to drive the probe. The result is a collection of splines that
create a wireframe for the port. Upon some manipulation of the
resulting data, a cutting toolpath can then be created.

Along with 5 Axis
digitizing, the probe also offers such digitizing procedures as
Radial Digitize, Grid Digitize, and Contour Digitize. The probe
is also very useful for doing CMM work, can be used to check
locations and positions of features and is a very useful tool to
measure dimensions that would be difficult or impossible to
reach with standard measurement tools.